Abstract: Abstract: In recent years, the phenomenon of CO exceeding the limit in the return air corner of the working face in Shendong mining area has become more and more serious, which seriously affects the safety production of coal mining enterprises. Therefore, taking 104-1 comprehensive mining face on 22 of Ohtai coal mine as the research object, a series of experiments were carried out, such as CO test of primary endowment in coal seams, test of CO production rate of coal at room temperature, test of CO production in the process of coal mining, and test of CO produced by exhaust gas of underground rubber wheel trucks, to investigate the main source of CO in the return air corner of comprehensive mining face. The study shows that about 75% of the CO is generated from the normal temperature oxidation of floating coal, 13% and 12% are generated from the coal cutter and the tail gas of rubber wheel trucks, and the primary CO in the coal seam is almost 0. The CO in the return air corner of the comprehensive mining face mainly comes from the oxidation of floating coal in the mining air space. By studying the source of CO, measures such as equal-pressure ventilation and spraying inhibitor were proposed to reduce the CO concentration in the return-air corner from 42 ppm to less than 10 ppm by reducing the oxidation of floating coal inside the air-mining area and preventing the leakage of CO in the air-mining area, which solved the problem of CO exceeding the limitation at the working face, and effectively ensured the safety production of theShi Ohtai Coal Mine.